/*
 * qsorter.c -- 用qsort() 排序一组数字 
 */


#include <stdio.h>
#include <stdlib.h>

#define NUM 40

void fillarray(double ar[], int n);
void showarray(const double ar[], int n);
int mycomp(const  void *p1, const void * p2);
int main(void)
{
    double vals[NUM];
    fillarray(vals, NUM);

    puts("Random list:");
    showarray(vals, NUM);
    qsort(vals, NUM, sizeof(double), mycomp);
    puts("\nSorted list:");
    showarray(vals, NUM);

    return 0;
}


void fillarray(double ar[], int n)
{
    for (int index = 0; index < n; index++) {
        ar[index] = (double) rand() / ((double) rand() + 0.1);
    }
}


void showarray(const double ar[], int n)
{
    int index;
    for (index = 0; index < n; index++) {
        printf("%9.4f ", ar[index]);
        if (index % 6 == 5) {
            putchar('\n');
        }
    }
    if (index % 6 != 0) {
        putchar('\n');
    }

}



int  mycomp(const void * p1, const void *p2)
{
    const double * a1 = (const double *) p1;
    const double * a2 = (const double *) p2;

    if (*a1 < *a2) {
        return -1;  
    } else if (*a1 == * a2) {
        return 0;
    } else {
        return 1;
    }
}

